Students solve word problems using the "discount" formula, which states: original price x rate of discount = discount. Students also solve word problems using the "sale price" formula, which states: original price – discount = sale price. For example: A tennis racket marked at $110.50 is on sale at 20% off. What is the discount? What is the sale price? Students also solve word problems using the "rate of discount" formula, which is the same as the percent decrease formula: amount of change/ original number. For example: An old video game is marked down from $48 to $18. What is the rate of discount?